Abstract

The influence of quantum confinement on the spin polarization of holes in ferromagnetic multiple quantum wells based on (Ga,Mn)As diluted magnetic semiconductor has been investigated. It is shown that the spin polarization of holes in the impurity band is more likely determined by the magnetic properties of GaMnAs rather than the quantum-confinement effect. The model of Mn acceptor in a QW, describing the polarization characteristics of photoluminescence in GaAs: Mn/AlAs QWs, has been developed. Experimental data and theoretical analysis show that the spin polarization of holes in (Ga, Mn)As/AlAs QWs can be explained within a model, which suggests that holes are localized in the impurity band.

@article{osti_22771525,
title = {Confinement effect on hole polarization in (Ga,Mn)As/AlAs diluted magnetic semiconductor multiple quantum wells},
author = {Dimitriev, G. S., E-mail: dimitriev@mail.ioffe.ru and Sapega, V. F. and Averkiev, N. S. and Panaiotti, I. E. and Ploog, K. H.},
abstractNote = {The influence of quantum confinement on the spin polarization of holes in ferromagnetic multiple quantum wells based on (Ga,Mn)As diluted magnetic semiconductor has been investigated. It is shown that the spin polarization of holes in the impurity band is more likely determined by the magnetic properties of GaMnAs rather than the quantum-confinement effect. The model of Mn acceptor in a QW, describing the polarization characteristics of photoluminescence in GaAs: Mn/AlAs QWs, has been developed. Experimental data and theoretical analysis show that the spin polarization of holes in (Ga, Mn)As/AlAs QWs can be explained within a model, which suggests that holes are localized in the impurity band.},
doi = {10.1134/S1063783417110063},
journal = {Physics of the Solid State},
issn = {1063-7834},
number = 11,
volume = 59,
place = {United States},
year = {2017},
month = {11}
}

We report on a study of the temperature-dependence of current-induced effective magnetic fields due to spin-orbit interactions in the diluted ferromagnetic semiconductor (Ga,Mn)As. Contributions from the effective fields as well as from the anomalous Nernst effect are evident in the difference between transverse resistance measurements as a function of an external magnetic field for opposite orientations of the applied current. We separately extract these contributions by fitting to a model of coherently rotating magnetization. The component of the effective field with Dresselhaus symmetry is substantially enhanced with increasing temperature, while no significant temperature-dependence is observed for the component with Rashbamore » symmetry.« less

We report upconversion photoluminescence (UCPL) in GaAs/AlAs multiple quantum wells. UCPL from the AlAs barrier is caused by the resonant excitation of the excitons in the GaAs well. When the quantum well has sufficient miniband width, UCPL is hardly observed because of the small exciton oscillator strength. The excitation-energy and excitation-density dependences of UCPL intensity show the exciton resonant profile and a linear increase, respectively. These results demonstrate that the observed UCPL caused by the saturated two-step excitation process requires a large number of excitons.

Magnetic tunnel junctions (MTJs) consisting of ferromagnetic metal (Cr{sub 1-{delta}}Te) and semiconductor (Ga{sub 1-x}Mn{sub x}As) electrodes with an AlAs tunnel barrier have been fabricated. A nonlinear behavior was clearly observed in the current versus bias-voltage characteristics, suggesting that the electric transport between the two ferromagnetic electrodes is tunneling. The MTJs exhibited the tunnel magnetoresistance (TMR) effect up to 14.5% at 5 K. The TMR ratio was observed to rapidly decrease with increasing temperature and bias voltage. These experimental results imply that Cr{sub 1-{delta}}Te is applicable to the spintronic devices based on III-V semiconductors.

We investigate industrial-grade InGaN/GaN quantum wells (QWs) emitting in the green spectral region under high, resonant pumping conditions. Consequently, an ubiquitous high energy luminescence is observed that we assign to a polarization field Confined Hole Continuum (CHC). Our finding is supported by a unique combination of experimental techniques, including transmission electron microscopy, (time-resolved) photoluminescence under various excitation conditions, and electroluminescence, which confirm an extended out-of-plane localization of the CHC-states. The larger width of this localization volume surpasses the QW thickness, yielding enhanced non-radiative losses due to point defects and interfaces, whereas the energetic proximity to the bulk valence band statesmore » promotes carrier leakage.« less